Open Accumulator Isothermal Compressed Air Energy Storage (OA-ICAES) system

Cost-effective, scalable and dispatchable energy storage systems is the key to integrating unpredictable and intermittent green energy, such as wind and solar energy, into the electrical grid. This chapter describes a novel Open Accumulator Isothermal Compressed Air Energy Storage (OA-ICAES) system for wind turbines that stores excess energy in the form of high pressure (210 bar) compressed air before conversion to electricity. The stored energy is then used to generate electricity when demand exceeds supply. The Open Accumulator architecture increases the system's energy density, whereas the isothermal compressor/expander increases the efficiency and power-density. They result in an efficient, cost-effective, hydrocarbon fuel-free energy storage system not restricted by geographic features to replace today's natural gas "peaker" plants. Since the system can turn on/off within a second, it can store and dispatch power rapidly on demand and can be used for frequency regulation. Because storage is prior to conversion to electricity, downstream electrical components (e.g. generator, transmission and interconnects) can be downsized for mean power instead of peak power. To realize isothermal compression/expansion, a liquid piston with porous media inserts, optimized trajectory and chamber designs, efficient power take-off, and water droplet sprays, are used. Plant and supervisory levels control systems coordinate and optimize the system performance.